Liquid atomizer



LIQUID ATOMI'LER 2 Sheets-Sheet 1 Filed Jan. 13, 1967 FIG] July 16, 1968 A. M. TROMMELEN LIQUID ATOMIZER 2 Sheets-Sheet 2 Filed Jan. 15, 1967 United States Patent 3,392,917 LIQUID ATOMIZER August Maria Trommelen, Vlaardingen, Netherlands, as-

signor to Unilever N.V., Rotterdam, Netherlands, a company of the Netherlands Filed Jan. 13, 1967, Ser. No. 609,055 Claims. (Cl. 239-214) ABSTRACT OF THE DISCLOSURE A liquid atomizer having a swirl chamber with a tangential inlet and an axial outlet, and in said chamber a power-driven rotor which co-acts with the outlet to atomize the liquid and can be driven at different high revolution speeds for varying the atomization effect without variation of the pressure of the liquid fed to the swirl chamber.

The invention relates to a liquid atomizer with a hollow swirl chamber and an axial outlet. In this type of liquid atomizer the liquid to be atomized has to be fed to the swirl chamber at a given capacity and under a relatively high pressure of 3070 atm., in order to give the liquid such a tangential and axial velocity that it emerges in the form of a thin conical film which falls apart into small droplets. During this operation a core of air is formed in the swirl chamber at the centre of the discharge opening. It is clear that the high feed pressure required at a given capacity of the atomizer is an unfavourable factor in the atomizing process, and moreover, the possibilities of enlarging an atomizer of this construction are only limited.

The object of the present invention is to effect the atomization at considerably lower liquid feed pressures by giving the liquid particles the required tangential velocity by mechanical means. For this purpose the liquid atomizer according to the invention is provided with an internal cylindrical power-driven rotor, located on the axis of the swirl chamber, which is capable of rotating at very high speeds adjacent to or within the axial outlet of the chamber.

The atomizer according to the invention has the additional advantage that it can be controlled while the pressure remains constant, since the speed of rotation of the rotor can be varied.

In the preferred embodiment the rotor has a smooth surface and projects into the discharge opening. The axial length of the surface bounding the axial outlet is limited to a maximum dimension in connection with the friction generated, and the distance from the rotor to the surface bounding the axial outlet is proportional to the axial length of said surface. The preferred embodiment is suitable for enlargement to scale according to the required capacity of the atomizer.

In a second embodiment of the invention the rotor is located adjacent the axial outlet and does not extend into it. In this second embodiment two different constructions of the rotor are possible. In one construction a shroud is provided around the rotor, the liquid particles then being forced to pass through the space between shroud and rotor on their way to the outlet. In the other construction a number of vanes are provided on the inward end of the rotor, which vanes are arranged in a circle in a common plane.

However, an atomizer with either a shrouded or vaned rotor is not suitable for enlargement to scale for an increased capacity and in this second embodiment the atomizer is restricted to a capacity of 1l /2 tons per hour. An example of a liquid atomizer according to the invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a sectional side elevation of a liquid atomizer according to the invention;

FIG. 2 is a fragmentary sectional side elevation of the preferred embodiment of the atomizer, showing only the swirl chamber and rotor;

FIG. 3 is a similar view to FIG. 2, showing an embodiment of the atomizer in which a shroud is provided around the rotor;

FIG. 4 is a similar view to FIG. 2, showing an embodiment of the atomizer in which vanes are provided on the rotor;

' FIG. 5 is a view in perspetcive of the rotor with vanes. FIGS. 1, 2., 3 and 4 are full-size drawings.

The hollow, cylindrical swirl chamber 1 has two tangential feeding channels 2 and an axial outlet 3 of 11.6 mm. diameter. On the axis of the chamber 1 a solid cylindrical rotor 4 is located, which is driven by an electric motor or a compressed air turbine 5 capable of rotating at at least 50,000 rpm. In the case of a larger axial outlet the number of revolutions may decrease inversely in proportion to the diameter. The space between the rotor spindle and a surrounding wall of the atomizer is supplied with compressed air, by means of compressed air conduits 6 to form a liquid seal. Naturally, other packings are also possible.

In the preferred embodiment the rotor projects into the axial outlet, as shown in FIGURE 2. The axial length of the surface 7 bounding the wall of the axial outlet is 1.6 mm., and the width 8 of the annular discharge outlet between the rotor and said surface is 0.4 mm.

In the embodiment shown in FIG. 3 the rotor extends up to a point spaced at distance of 11 /2 mm. from the axial outlet, in order to prevent clogging besides keeping the thickenss of the discharge conical film between specific limits. A cylindrical shroud 9 is provided around the rotor at such a distance 10 from it that the resistance offered to the liquid flow is as low as possible, this distance being 2-4 mm. The shroud 9 ends at some distance from the rear wall of the swirl chamber, but is provided at its other end with a flange 11, which is at a distance of 0.1 mm. from the swirl chamber front wall and forms a barrage for the greater part of the liquid stream. The diameter of the rotor is equal to, or substantially equal to, that of the axial outlet of the swirl chamber.

The embodiment shown in FIG. 4 is, in principle, equivalent to that of FIG. 3, but in FIG. 4 the rotor is provided with vanes 12, which are arranged in a circle in a common plane on the upper section of the rotor. The vanes 12 are shaped as indicated in FIG. 5, having a height of about 4 mm., and are arranged at an angle of 45 relative to the axis of the rotor.

The liquid atomizer according to the invention operates according to the principle of the generally known hollow swirl chamber and needs no further description. As already stated, the big advantage of this atomizer is the fact that it can be enlarged to scale, at least in the preferred embodiment of FIG. 2, and that the liquid to be atomized can be fed at a constant pressure and at a lower pressure than in a conventional atomizer.

The film thickness of the dicharged liquid particles obtained with the embodiment of FIG. 3 is less than with the embodiment shown in FIG. 4, because of a higher tangential velocity imparted to the liquid particles at an identical speed of rotation of the rotor.

The liquid atomizers according to FIGS. 3 and 4 are not suitable for enlargement to scale, because in that case a supersonic speed of rotation of the rotor would be required.

I claim:

1. In a liquid atomizer, the combination of means defining a cylindrical swirl chamber with at least one tangential inlet and an axial outlet, cylindrical rotor within said chamber, means mounting said rotor co-axially with said axial outlet and in co-acting relationship therewith to define an annular discharge outlet between said rotor and the boundary of said axial outlet, and drive meansoperative to rotate said rotor at a minimum speed of 50,000 revolutions per minute.

2. Liquid atomizer according to claim 1, wherein the rotor projects into the axial outlet, and the annular discharge outlet is formed by an annular gap between the rotor and the surface bounding the axial outlet.

3. Liquid atomizer according to claim 1, wherein the rotor is located adjacent the axial outlet and does not extend into it.

4. Liquid atomizer according to claim 3, wherein the rotor is surrounded by a spaced cylindrical shroud.

5. Liquid atomizer according to claim 3, wherein the rotor is provided with a ring of spaced vanes set at an 5 angle to the rotor axis.

References Cited UNITED STATES PATENTS 5/1955. Schmidt 239 -3s0 x 2/1961 Gurley 259-7 M. HENSON WOOD, JR.,' Primary Examiner. H. NA'ITER, Assistant Examiner. 

